The present invention relates to a metering valve assembly for dispensing a premeasured quantity of a product from an aerosol container once the stem of the aerosol valve is sufficiently depressed.
A number of metering valves are currently available in the market place. Most of these currently available metering valves utilize a ball or some other additional component which has to be separately installed in the valve housing to ensure proper metering of a desired quantity of an aerosol product from the valve assembly upon sufficient actuation or depression of the stem. The installation of this additional component, during manufacture of the aerosol valve, generally increases the production costs as well as the inspection costs associated with manufacture of the aerosol valve. Moreover, if the additional component is not properly installed or is omitted from the valve assembly for some reason, the aerosol valve will malfunction. Accordingly, an inspection step is generally required, following installation of the additional component, to confirm that the additional component was, in fact, properly installed within the aerosol valve.
Another drawback associated with prior art metering valves is that such valves have a tendency to xe2x80x9cthrottlexe2x80x9d. That is, due to a poor or an improper valve design, it is possible for an operator to partially depress the valve stem and establish a product flow path from the interior cavity of the aerosol container through the metering valve and out through a spray button or an actuator affixed to the stem of the aerosol valve, prior to the valve stem sealing the inlet to the valve housing, so that product may be continuously discharged out through the aerosol valve. As a result of such throttling, the operator is able to dispense a continuous discharge of product from the aerosol container via the metering valve. This results in the inadvertent discharge of excess product from the aerosol container which is wasteful and generally to be avoided.
Another prior art design utilizes a frictional sealing fit between two plastic valve components to separate the contents of the container from the metering chamber. This arrangement requires that the valve spring be sufficiently forceful to overcome the interference fit of this sealing device upon the valve closing sequence. Apart from being subject to size and hardness changes due to immersion in the product, this design mandates extremely close tolerances of the mating components and critical alignment of molded parts during the valve assembly operation. Failure to observe these manufacturing tolerances and alignment criteria leads to an inaccurate metered spray or a valve which will not xe2x80x9cshut-offxe2x80x9d and thus result in the total release of the entire product contents.
Wherefore, it is an object of the present invention to overcome the above noted drawbacks associated with the prior art aerosol metering valves.
Another object of the present invention is to minimize the amount of separate components that must be separately assembled, during manufacture of the valve assembly, to improve the easy of assembly of the metering valve assembly.
Yet another object of the present invention is to provide a metering valve assembly which reliably, consistently and accurately dispenses a desired quantity of the product contents from the metering valve assembly.
A still further object of the present invention is to provide a metering valve assembly which can be reliably manufactured while minimizing the degree of inspection required for manufacture of the metering valve assembly.
A further object of the present invention is to provide a metering valve assembly which prevents inadvertent xe2x80x9cthrottlingxe2x80x9d of the metering valve assembly by an operator.
The present invention also relates to a ferrule having an aperture formed therein; a valve housing having an inlet provided in a base wall thereof, the valve housing defining an internal cavity which accommodates an annular flange of a valve stem and a compression spring therein, and a valve gasket closing the internal cavity; the valve housing being attached to the ferrule such that a stem portion of the valve stem protrudes through an aperture provided in the valve gasket and through the aperture provided in the ferrule; and the stem portion having a passageway formed therein communicating with a dispensing outlet, and an opposite end of the passageway communicating with at least one radial passageway; and the at least one radial passageway being normally closed by the valve gasket due to the spring normally biasing the valve stem into a closed position; wherein one of an undersurface of the annular flange of the valve stem and a mating surface of the valve housing is provided with an compressible sealing member and the other of the undersurface of the valve stem and the mating surface of the valve housing is provided with an annular sealing edge, and the compressible sealing member and the annular sealing edge form a seal therebetween, when the valve stem is sufficiently depressed, to partition the interior cavity into a metering chamber and a separate filling chamber so that product may be dispensed solely from the metering chamber when a product flow path is established between the metering chamber and the dispensing outlet of the valve stem.
The present invention also relates to a method of metering dispensing of product through a metering valve assembly, the method comprising the steps of: forming an aperture in a ferrule; providing an inlet in a wall of a valve housing and defining, via the valve housing, an internal cavity which accommodates an annular flange of a valve stem and a compression spring therein, and closing the internal cavity by a valve gasket; attaching the valve housing to the ferrule such that a stem portion of the valve stem protrudes through an aperture provided in the valve gasket and through the aperture provided in the ferrule; and forming a passageway in the stem portion which communicates with a dispensing outlet of the metering valve assembly, while an opposite end of the passageway communicates with at least one radial passageway; and normally closing the at least one radial passageway the valve gasket due to the spring normally biasing the valve stem into a closed position; providing one of an undersurface of the annular flange of the valve stem and a mating surface of the valve housing with an compressible sealing member and providing the other of the undersurface of the valve stem and the mating surface of the valve housing with an annular sealing edge, and forming a seal between the compressible sealing member and the annular sealing edge when the valve stem is sufficiently depressed, to partition the interior cavity into a metering chamber and a separate filling chamber, so that product may be dispensed only from the metering chamber when a product flow path is established between the metering chamber and the dispensing outlet of the valve stem.
In the following description and appended drawings, the terms xe2x80x9cinwardxe2x80x9d and xe2x80x9cdownwardxe2x80x9d mean toward a lower bottom portion of the respective drawing while the terms xe2x80x9ctopxe2x80x9d and upwardxe2x80x9d mean toward an upper portion of the respective drawing.